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Mesoscopic Scale (mesoscopic + scale)
Selected AbstractsQuantitative Phase Field Modeling of Precipitation Processes,ADVANCED ENGINEERING MATERIALS, Issue 12 2006Q. Bronchard Phase Field modelling of microstructural evolution in alloys has already a long and successful history. One of the basics of the theory is the introduction of continuous fields (concentration, long-range order parameters) that describe the local state of the alloy. These fields have a meaning only at a mesoscopic scale. One consequence is that we can treat much larger systems than with microscopic methods such as Monte Carlo or molecular dynamics simulations. The aim of this work is to precisely analyse the status of the mesoscopic free energy densities that are used in Phase Field theories and, simultaneously, to clarify the form that the Phase Field equations should adopt. [source] Constraints on deformation mechanisms during folding provided by rock physical properties: a case study at Sheep Mountain anticline (Wyoming, USA)GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2010K. Amrouch SUMMARY The Sheep Mountain anticline (Wyoming, USA) is a well-exposed asymmetric, basement-cored anticline that formed during the Laramide orogeny in the early Tertiary. In order to unravel the history of strain during folding, we carried out combined anisotropy of magnetic susceptibility (AMS), anisotropy of P -wave velocity (APWV) and Fry strain analyses. The results are compared to previously published stress,strain data from calcite twins at the microscopic scale and from fracture sets at the mesoscopic scale, and are used to discuss the kinematics and mechanics of forced folding. The results obtained in sandstone and carbonate lithologies demonstrate a good agreement between (1) the principal axes of the AMS and APWV tensors, (2) stress,strain tensors derived from calcite twins, (3) Fry strain axes and mesoscopic fracture sets. Furthermore, these tensors are coaxial with the main structural trends of the anticline. The differences between AMS and APWV fabrics on one hand, and the differential stress values of the forelimb and the backlimb on the other hand, emphasize how the macroscopic asymmetry of Sheep Mountain anticline affects the strain pattern at the microscopic scale. The data set presented in this paper offers a consistent mechanical scenario for the development of Sheep Mountain anticline. [source] A mesoscopic model for the behaviour of concrete under high confinementINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 11 2009F. Dupray Abstract When impact loaded, concrete is submitted to high triaxial stresses. The experimental response of concrete under quasi-static triaxial compression is studied using a triaxial press capable of applying a mean pressure greater than 1,GPa on cylindrical samples measuring 7,cm in diameter and 14,cm high. A numerical analysis of these previous experiments is performed herein at a mesoscopic scale. Concrete is modelled as a biphasic material consisting of a mortar (cement paste and fine aggregates) and roughly spherical aggregates (with a diameter exceeding 2,mm) whose characteristics are applied on a regular cubic finite element mesh. A damage-plasticity model is then used to model the behaviour of mortar. An identification of model parameters on mortar samples and the subsequent comparison between numerical and experimental tests will be presented for hydrostatic and triaxial compression. Copyright © 2009 John Wiley & Sons, Ltd. [source] Examination of whewellite kidney stones by scanning electron microscopy and powder neutron diffraction techniquesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2009Michel Daudon Kidney stones made of whewellite, i.e. calcium oxalate monohydrate, exhibit various morphological aspects. The crystalline structure of whewellite at the atomic scale was revisited through a single-crystal neutron study at room temperature using a four-circle automated diffractometer. The possible relationships between the various morphological types of whewellite stones and their structural characteristics were examined at the mesoscopic scale by the use of scanning electron microscopy and at the nanometric scale by powder neutron diffraction. All types of whewellite stones displayed a similar structure at the nanometric scale. However, significant differences were found at the mesoscopic scale. In particular, the crystallites in kidney stones resulting from a genetic hyperoxaluria exhibited a peculiar structure. There was a close relationship between stone morphology and crystallite organization at the mesoscopic level and the effectiveness of extracorporeal shockwave lithotripsy. [source] Time-resolved resonance Raman study on ultrafast structural relaxation and vibrational cooling of photodissociated carbonmonoxy myoglobinBIOPOLYMERS, Issue 4-5 2002Teizo Kitagawa Abstract A localized small structural change is converted to a higher order conformational change of protein and extends to a mesoscopic scale to induce a physiological function. To understand such features of protein, ultrafast dynamics of myoglobin (Mb) following photolysis of carbon monoxide were investigated. Recent results are summarized here with a stress on structural and vibrational energy relaxation. The core expansion of heme takes place within 2 ps but the out of plane displacement of the heme iron and the accompanying protein conformational change occur in 10 and 100 s of the picosecond regimes, respectively. Unexpectedly, it was found from UV resonance Raman spectra that Trp7 in the N-terminal region and Tyr151 in the C-terminal region undergo appreciable structural changes upon ligand binding,dissociation while Tyr104, Tyr146, and Trp14 do not. Because of the communication between the movements of these surface residues and the heme iron, the rate of spectral change of the iron-histidine (Fe- His) stretching band after CO photodissociation is influenced by the viscosity of solvent. Temporal changes of the anti-Stokes Raman intensity demonstrated immediate generation of vibrationally excited heme upon photodissociation and its decay with a time constant of 1,2 ps. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 207,213, 2002 [source] Tectonics and quaternary evolution of the Northern Apennines watershed area (upper course of Arno and Tiber rivers, Italy)GEOLOGICAL JOURNAL, Issue 1 2009Marco Bonini Abstract This work examines the connection between Quaternary tectonics and erosion/incision processes in the primary Tuscan-Romagna watershed of the Northern Apennines, which essentially coincides with the topographic culmination of the Nero Unit structural ridge. Tectonic and geomorphic information were collected in the area where this ridge is crossed by the upper Tiber River course forming a deep gorge. Structural analysis and field mapping have revealed that the region experienced polyphase tectonics with superposed thrust folding events identifiable both at the map and mesoscopic scales. Hinterland-SSW-verging thrusts and thrust-related folds deformed the whole thrust pile during the latest deformation phase. Backthrusts/backfolds controlled the development of intermountain basins nearby the main watershed during the Early Pleistocene and seemingly deformed, in the Tiber gorge, a low-relief landscape developed in the Early Pleistocene (ca. 1.1,Ma). Successively, the upper Tiber River course area and Apennines axial zone underwent a generalized uplift, which is manifested by the deep incision of palaeo-morphologies. This proposed sequence of events correlates well with the major geodynamic change of the Apennines revealed by an acceleration of uplift rates in the Middle,Late Pleistocene. This latter event may also correlate with increased rates of river incision recorded in Europe as a consequence of uplift and/or climate change. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||